In a very promising step, it looks like that venerable CMF Drupal is beginning to take on the process of becoming microformatted with the creation of the Microformats in Drupal group.
The original use of microformats came in the Upcoming.org module (I believe) but now it seems clear that there are many more places throughout Drupal that could benefit from microformats, including on the content creation side.
With word that OpenID support will be added to Drupal Core in version 6 (a module is already available for 4.7), if we see the addition of hcard for profiles and XFN for representing social relationships in Drupal, we may finally be moving towards a more decentralized, open-source network of socially adept web properties.
Factory Joe 
Hey Chris, thanks for pointing out our group. Hopefully members of the Microformat community will join in and discuss what steps they would like to take in implementing microformats in Drupal.
From the relatively easy integration of hAtom, to supporting hCard and hCalendar output in existing modules, this will be the place to discuss it.